1. Field of the Invention
The present invention relates to semiconductor memory devices and, more specifically, to a three-dimensional semiconductor memory device and a programming method thereof.
2. Description of the Related Art
In order to meet ever-increasing needs of the users for superior performance and low costs, there is a requirement for high integration density of semiconductor memory devices. Since integration density of semiconductor memory devices is significant in determining the price of products, there is a requirement for increased integration density. In case of conventional two-dimensional semiconductor memory devices, their integration density is mainly determined by an area occupied by a unit memory cell. Therefore, the conventional two-dimensional semiconductor memory devices are greatly affected by fine-pattern forming technologies. However, because extremely high-priced apparatuses are needed to achieve fine patterns, the integration density of two-dimensional semiconductor memory devices is still limited.